The R845A1030 from Honeywell is a Switching Relay, DPST. It provides intermediate switching of a line voltage device form a low voltage controller. These relays may be directly controlled by any 2-wire series 80 thermostat, such as the T86A Round Thermostat or T852A Electric Clock Thermostat.
Honeywell R845A1030 provides DPST switching for hydronic zone controlled heating systems or SPST control of two seperate loads. One load must be line voltage; the other may be either line or low voltage.

Features:

• Integral transformer provides low voltage power for control circuit;
• Includes integral transformer, enclosure;
• Approvals of Underwriters Laboratories Inc and Canadian Standards Association

Technical Specifications:

• Switching Action: DPST; one pole line voltage, the other line or low voltage;
• Coil Ratings Current: 0.4A;
• Coil Ratings Voltage: 24V;
• Transformer Primary Rating: 120V, 50/60 Hz;
• Transformer Secondary Rating: 24V;
• Temperature Range: 115F maximum ambient for 60 Hz. 105F Max. Ambient for 50 Hz;
• Thermostat Compatibility: Low voltage (Class 2) 2-wire;
• Dimensions: 5 1/4" high x 4 1/4" wide x 2 5/16" deep;
• Electrical Connections (Control Circuit): 2-Wire;
• Electrical Ratings: Maximum input: 5W;
• Contacts Electrical Rating Main Contacts 120 Vac: 7.4A AFL; 44.4A ALR; 10A Resistive;
• Contacts Electrical Rating Secondary Contacts 120 Vac: 3A ALF; 18A ALR;
• Contacts Electrical Rating Main Contacts 240 Vac: 3.7A ALF; 22.2A ALR; 6.0A Resistive;
• Contacts Electrical Rating Secondary Contacts 240 Vac: 2A AFL; 12A ALR;
• Contacts Electrical Rating Secondary Contacts Pilot Duty Rat: 50 VA @ 24V;
• Contacts Electrical Rating Contacts Max. Connected Load: 2000 VA (120 Vac to 240 Vac);
• Electrical Ratings (Primary Voltage): 120V, 50/60 Hz;
• Tradeline Value: Tradeline.